Also, some might suggest bots, and scripts to auto-remove comments and posts to help for moderation. While this might indeed help, there still needs increase in mods eventually if the userbase grows, but maybe less more than it is needed without any scripts.

Think like this: You need to go from point A to point B. You can do it walking, you can use a bicycle, or you can use a car. All of them needs energy (moderators). Some more than others. If you use tools, you need less, but still you need to use it. And if the distance of these two points become bigger, you need more energy, but of course a car helps tremendously, but still you need to focus on the car and use energy.

So a 1 person moderators with all the tools, bots and filters won't help much if there is an user-base of millions in the community.